1. Field of the Invention
The present invention relates to an endoscope having an insertion portion including an image pickup portion to be inserted into a body cavity or an abdominal cavity during diagnosis, inspection or therapy, and to a hydrophilic cap to be attached to this endoscope.
2. Description of the Related Art
In recent years, endoscopes have been widely used that can perform diagnosis, inspection or therapy of organs, biological tissues, etc., in a body cavity or abdominal cavity. The endoscopes include, for example: a flexible endoscope including a flexible insertion portion to be inserted from an anus or oral cavity into a body cavity such as a large intestine, stomach, etc.; and a rigid endoscope including a rigid insertion portion to be inserted from an incised portion into a body for operation in the abdominal cavity under the endoscope observation.
These endoscopes include a lens unit to obtain an image of an organ, etc., and an image pickup device or an image pickup portion such as a glass fiber-made image guide fiber and a relay lens. On a distal end surface of the insertion portion of the endoscope, a cover member with light transparency is provided in front of the lens unit. A surface of this cover member configures one outer surface of the distal end surface of the insertion portion.
When the insertion portion of the endoscope is inserted into a body cavity or abdominal cavity, the cover member is in some cases fogged because of a temperature difference between the outside air and the inside of the body cavity. Accordingly, to prevent the fogging of the cover member, as described in, e.g., Japanese unexamined patent publication No. 7-275185, a technique is disclosed to remove fogging by covering the insertion portion with a sheath having a cleaning nozzle to spray a fluid on a surface of a cover member subjected to a defogging processing.
Further, as described in, e.g., Japanese Unexamined Patent Publication No. 2004-267583, a technique is disclosed to prevent fogging by forming a thin film containing a photocatalyst on a surface of a cover member for hydrophilization. This endoscope can prevent the fogging because even if the surface of the cover member is adhered with a liquid such as a body fluid in the body cavity or abdominal cavity, water caused by humidity, and a physiological saline solution, the liquid becomes a water film that is evenly wet and spread.